1. Field of the Invention
The present invention generally relates to client/server technology and, more specifically, to a client/server architecture for occasional connections between mobile computing devices and enterprise computing systems.
2. Background
In the current persistent connection client/server model, personal computer clients "connect" to a server on the network and request data from the server as needed by an application. This is usually performed by use of SQL (Structured Query Language). The connection between the client and server exists the entire time the application is in use, usually for hours at a time. This is not possible in a mobile model, because it is not possible for mobile clients to remain connected for that amount of time. Mobile clients connect on an occasional basis, and when they do connect, the connection needs to move the smallest amount of data in the least amount of time. This is because wireless transports are not capable of moving large of amounts of data quickly, and data is extremely expensive to move.
Existing client/server technologies based on persistent network connections were not designed to support occasional connections between low performance, low overhead handheld computing devices and existing enterprise computing systems. What is needed is a client/server architecture that supports occasional connections between low performance, low overhead mobile computing devices and existing enterprise computing systems. What is desired is an application development and deployment platform, such that developers have the ability to create applications using a series of forms, tables, and communications agents, and the ability to deploy and maintain these applications. This platform should be implemented using an object model that can be easily ported to other hardware platforms and operating systems.
An architecture that allows multiple devices to connect concurrently to a single server is desired. This architecture should allow developers to connect any existing enterprise data source to handheld clients in the field. This architecture should allow developers to create two way links between any existing enterprise data source on a network, such as a database, mail server, or internet news feed, and FormLogic client applications.
The improved client/server architecture should provide "transport independence", which is a unique requirement of field based applications. Sometimes it is necessary to connect over a serial cable, other times over a wireless local area network (LAN), and other times over the Internet. Such functionality has been addressed with "middleware" products. However, middleware products usually consist only of a series of "C" application programming interfaces (APIs) on client and server ends that require the developer to integrate them into an application. What is desired is to integrate "middleware" functionality directly into a specific server structure for which developers create "services".
Existing client/server APIs move a tremendous amount of data, such as Microsoft.TM.'s ODBC (Open Database Connectivity). It is not feasible to use interfaces such as ODBC in the handheld or occasionally connected environment for two reasons. 1) The code size of ODBC is several megabytes--more than the entire memory of today's handheld devices and 2) ODBC is designed to work over a persistent connection with high bandwidth, such as Ethernet. Therefore, what is desired is a set of client/server APIs that can utilize a variety of transports to move a minimum amount of data over the wire or through the airways. To accommodate current and future transports, a message-based asynchronous communications protocol that is designed to work efficiently over low bandwidth, high latency networks is needed. This capability is required for evolving wireless transports, such as these provided by the companies of ARDIS.TM., RAM Mobile Data.TM., and 2-way paging, such that developers will automatically be able to support them without making any changes to their applications.
Application software on a client device may not be the most recent available due to enhancements, fixes, and so forth. The architecture should support a users and groups model, wherein different applications modules can be distributed to a particular user or group. Using a version control for these applications components, users can automatically be updated with the latest version of an application upon connection.